1. Field of the Invention
Exemplary embodiments relate to a liquid crystal display device and a dimming controlling method thereof.
2. Discussion of the Related Art
The active matrix liquid crystal display device represents moving pictures using the thin film transistor (or “TFT”) as the switching elements. Comparing to the cathode ray tube (or “CRT”), the liquid crystal display device can be made in small size and light weight so that it can actively applied to the portable information devices, office automation devices, and computers. Further, it can be effectively applied to the television set replacing with the CRT.
As the liquid crystal display device is not self-luminescent element, the liquid crystal display device requires a backlight unit for irradiating light to the liquid crystal display panel. The video quality of the liquid crystal display device is mainly dependent on the characteristic of contrast. With only controlling of the light transmittance at the liquid crystal layer of the liquid crystal display panel, it is restricted to improve the characteristics of the contrast. To improve the characteristics of the contrast, the backlight dimming control method is suggested in which the luminescence of the backlight unit is controlled. By actively controlling the luminescence of the backlight, the backlight dimming control method can reduce the consumption power. In the backlight dimming method, there are the global dimming method in which all luminescence of the display panel is controlled at the same time, and the local dimming method in which the luminescence of the display panel is controlled partially. The global dimming method was developed to improve the dynamic contrast measured between the previous frame and the next frame. The local dimming method was developed to improve the static contrast hard to be accomplished by the global dimming method, by controlling the luminescence of the display panel partially within one frame. However, the conventional local dimming method causes the luminescence unevenness and flickers between neighboring blocks divided in the display panel. Further, for realizing the local dimming circuit, a lot of circuit elements are required so that the circuit configuration is complex and the algorithm for driving the circuit is very complicated.